A field experiment for the study of ground motion variation across a topographic relief, based on explosions and microtremors recordings, was carried out. The hill selected for the experiment is located in Northern Greece, close to the Lagada lake, about 15 km NW of the Euroseistest experimental test site. It is constituted by quite homogeneous metamorphic rocks. The experiment consisted in the execution of four explosions at the toe of the hill. Ground motion was recorded at the crest, at the toe and along the flanks. Between explosions, data acquisition at the crest proceeded continuously to record ambient noise. The explosion data were used to construct experimental seismic sections to study the scattered wavefield. They also were processed using standard spectral ratios (SSR) between the station at the crest and those at the toe and along the flanks showing topographic relative amplification between these points. In addition, horizontal to vertical spectral ratios (HVSR) were also computed both using explosion data and ambient noise recordings in order to explore the applicability of this non-reference technique in estimating topographic effects. Finally, experimental HVSR at crest were compared with those obtained from numerical modeling with a bidimensional boundary element code showing a good agreement at least in terms of spectral shape.
Experimental study of topographic effects using explosions and microtremors recordings
PAGLIAROLI, Alessandro;
2007-01-01
Abstract
A field experiment for the study of ground motion variation across a topographic relief, based on explosions and microtremors recordings, was carried out. The hill selected for the experiment is located in Northern Greece, close to the Lagada lake, about 15 km NW of the Euroseistest experimental test site. It is constituted by quite homogeneous metamorphic rocks. The experiment consisted in the execution of four explosions at the toe of the hill. Ground motion was recorded at the crest, at the toe and along the flanks. Between explosions, data acquisition at the crest proceeded continuously to record ambient noise. The explosion data were used to construct experimental seismic sections to study the scattered wavefield. They also were processed using standard spectral ratios (SSR) between the station at the crest and those at the toe and along the flanks showing topographic relative amplification between these points. In addition, horizontal to vertical spectral ratios (HVSR) were also computed both using explosion data and ambient noise recordings in order to explore the applicability of this non-reference technique in estimating topographic effects. Finally, experimental HVSR at crest were compared with those obtained from numerical modeling with a bidimensional boundary element code showing a good agreement at least in terms of spectral shape.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
